1. Field of the Invention
The present invention relates to a magnetic head and more particularly to a magnetic head which performs magnetic recording or reproduction of information to or from a magnetic recording medium by slidably contacting a magnetic core, around which a coil is wound, the magnetic recording medium.
2. Description of the Prior Art
In the field of magnetic recording, metal type magnetic recording medium have hitherto been used. The metal type magnetic recording medium has a high coercive force and a high residual magnetic flux density according as recording signals with higher densities. For this reason, it is required that a material for constructing a core of a magnetic head for performing magnetic recording or reproduction has a high saturated magnetic flux density and a high magnetic permeability.
However, a ferrite, which is a ferromagnetic oxide that has hitherto been used most widely as a core element, fails to give satisfactory characteristics. Therefore, in order to obviate this disadvantage, metal-in-gap type magnetic heads have recently been put in practice widely in place of conventional ferrite heads of which all the magnetic paths of their magnetic cores are made of a ferrite. The metal-in-gap type magnetic heads are composite heads each including a pair of magnetic core halves made of a ferrite that the magnetic core halves are opposite to each other through a magnetic gap element and whose surfaces are provided thereon with a magnetic metal film having a high saturated magnetic flux density and made of a metallic material, for example Sendust or amorphous alloy that is formed by a vacuum film formation technique such as sputtering vapor deposition, ion plating, or the like.
The metal-in-gap type magnetic heads of the above-described construction, however, are still disadvantageous in that because of heat treatment at a high temperature as high as, e.g., from about 500.degree. to 600.degree. C., in a step of weld of glass which is indispensable to a process for the fabrication of magnetic heads, a diffusion reaction occurs at an interface between the above-described ferromagnetic oxide and the magnetic metal film, thus forming a reaction prevention film having deteriorated soft magnetic characteristics. The reaction prevention film serves as a quasi-gap or false gap to give rise to a quasi-peak or false peak due to its interference with a magnetic flux of the true magnetic gap portion. As a result, swells are formed in a frequency characteristics curve of reproduced signals so that a so-called contour effect is produced. This problem has conventionally been coped with by making use of an azimuthal effect, more particularly by providing an azimuth angle so that a junction portion which would serve as a false gap and a magnetic gap portion are arranged non-parallel to each other. However, with the above-described construction, it is necessary to provide a thick magnetic metal film. For example, in case of fabricating a magnetic head for a still video camera, or VTR, i.e., video tape recorder which has a track whose width is in the range of from 10 to 60 .mu.m, it is necessary to provide a magnetic metal film in thickness of 20 to 30 .mu.m. When the thickness is not in the above-described range, it causes a problem that yield of products decreases because of peeling off of films or it takes a long time to form deposits, thus decreasing productivity.